My initial CPL application was rejected due to being 35 minutes short - an error that the Instructor and I had both failed to spot early on, and had got compounded. They sent everything back & told me to go complete the course! Thankfully it did not negate the skills test I had just passed.
That 35 mins cost me a lot more than it would have done had it been tacked onto a normal flight.
So yes, they most certainly do check your logbook, both for accuracy, and possibly a few G-BIRO entries as has been alluded to by 4S.
DW.